Miniature robotic aircraft could soon have insect-like eyes to go with their insect-like wings. Neurobiologists have developed an artificial bee eye, with a 280-degree field of vision, which should enable robots to see more of the world around them.
Wolfgang Stürzl and colleagues at Bielefeld University in Germany wanted to capture as wide-angled a view of the world as possible using a single camera, in order to minimise the weight of robotic aircraft. To do this, the team used a so-called catadioptric imaging system, which captures an image using both mirrors and lenses.
In their set-up, a dome-shaped mirror, with a lens at its centre, was placed 20 millimetres in front of the camera's charge-coupled device (CCD) image sensor chip, with its convex surface facing towards the camera. The lens focuses light from in front of the camera onto the CCD to create an image with a 110-degree field of view. At the same time, the convex face of the mirror captures a reflection of the world behind the camera and focuses this light onto the CCD, widening the field of view to 280 degrees.
A computer algorithm stitches the two sets of images together, creating a composite image that looks as if it was captured through a fisheye lens. The small computer on board the robotic aircraft should be able to perform this stitching job fast enough to run at 25 frames per second, say the team.
Finally, to represent 280 degrees of information as a 2D image, the composite image passes through a system that mimics the several thousand hexagonal facets of the honeybee's compound eyes. This reduces the resolution of the image, but makes it easier for whoever is controlling the robot to interpret the extremely wide-angled view of the world.
Hod Lipson, a roboticist at Cornell University in Ithaca, New York, says the honeybee lens is a "great contribution to robotics and especially to micro air vehicles where wide field vision systems need to be packed into a very compact space". He says that the vision system is one of many aspects of insect morphology, physiology and behaviour that could be mimicked in robotics. Others include insects' flight stability, their resilience to a range of environmental conditions, and extreme power efficiency.
Journal reference: Bioinspiration & Biomimetics, DOI: 10.1088/1748-3182/5/3/036002.
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